The present invention, in some embodiments thereof, relates to methods and systems of imaging and, more particularly, but not exclusively, to methods and systems of medical localizing and monitoring as well as to imaging using a functional imaging modality, e.g., a single photon emission computed tomography (SPECT) and/or positron emission tomography (PET).
Volumetric scans such as CAT scans, positron emission tomography (PET) scans, computerized tomography (CT) scans, magnetic resonance imaging (MRI) scans, Ultrasound scans, laser three dimensional (3D) scanners, and the like are commonly used, particularly in the medical industry, to observe objects within a structure that would otherwise be unobservable. These scans have greatly advanced the capability of professionals such as physicians. Conventional volumetric scan is intended to produce a volumetric image of a large volume of the body at high resolution. The ability to perform a volumetric scan with high resolution requires a large number of detectors, a fine motion control, and abundant processing resources for allowing the acquisition of a high resolution volumetric image in a reasonable time. Furthermore, when the volumetric scan images a relatively large area, such as the torso, the patient radiation dose is relatively high, for example when the volumetric scan is a CT scan.
Usually, volumetric imaging of a body structure is a multi-stage process. First biochemical, radioactive and/or contrast agents may be administered. Then, measurements are taken at a set of predetermined views at predetermined locations, orientations, and durations. Then, the data is analyzed to reconstruct a volumetric image of the body structure and an image of the body structure is formed. The imaging process is sequential, and there is no assessment of the quality of the reconstructed image until after the measurement process is completed. Where a poor quality image is obtained, the measurements must be repeated, resulting in inconvenience to the patient and inefficiency in the imaging process.
The volumetric scan is usually performed by orbiting detectors from multiple directions in order to provide sufficient information to reconstruct a three-dimensional image of the radiation source by means of computed tomography. The detectors are typically mounted on a gantry to provide structural support and to orbit the detector around the object of interest. If the detector is a nuclear medicine detector, such as scintillation detector or CZT detectors, for example single photon emission computed tomography (SPECT) and positron emission tomography (PET) systems detector, a collimator that is used to restrict radiation acceptance, or the direction of ray travel, is placed between the detector and the object being imaged. Typically this collimator is constructed to provide a multiplicity of small holes in a dense, high-atomic-number material such as lead or Tungsten. The rays will pass through the holes if they travel in a direction aligned with the hole but will tend to be absorbed by the collimator material if they travel in a direction not aligned with the holes.